Induction heating apparatus



FIG. I

Oct. 9, 1962 Fild July 18, 1960 w gm R. G. ARMSTRONG ETAL INDUCTION HEATING APPARATUS 2 Sheets-Sheet 1 JIK/JNVENTORS OBERT G. ARMSTRONG JOHN R. LAUGHLIN BY i g I ATTORNEY Oct. 9, 1962 R. G. ARMSTRONG ETAL 3,957,986

' INDUCTION HEATING APPARATUS Filed July 18, 1960 2 Sheets-Sheet 2 INVENTORS ROBERT G. ARMSTRONG a J( HN R. LAUGHLIN ATTORNEY United States Patent 3,057,986 UCTION HEATING APPARATIE Robert G. Armstrong, Euclid, and John R. Laughlin,

Broadview Heights, Ghio, assignors to The Ohio Crankshaft Company, Cleveland, Ohio, a corporation of Ohio Filed July 18, 1%0, Ser. No. 43,534 Claims. (Cl. 2l910.59)

This invention relates to an induction furnace for heating metal billets and the like, and more particularly to an induction heating furnace adapted to heat billets of various sizes and shapes.

Induction heating furnaces for metal billets and the like comprise an elongated induction coil having means at one end to feed a succession of billets axially forwardly into the interior of the coil assembly. In the usual induction furnace of this type, provision must be made for heating different sized billets. For the most efiicient heating, a coil of the exact size to lit the workpiece must be employed. Usually a coil of such exact cross-sectional size or shape is bolted to a base member, the arrangement being such that when billets of different sizes or shapes are to be heated, the coil must be unbolted from the base and replaced by another coil of the proper configuration for the particular billets to be heated. This procedure requires a substantial amount of changeover time while the mounting bolts, bus bar connections and cooling hoses are disconnected and the coil replaced by another which must then be aligned with the billetpushing mechanism and bolted in place with the proper electrical and cooling connections. Storage space must be provided for the coils of various sizes and shapes while they are not in use, and the possibility always exists of damage to the coils from repeated handling during change-overs.

The present invention has as its primary object the provision of apparatus for inductively heating Workpieces of various shapes and sizes.

More specifically, an object of the invention is to provide an induction heating furnace for workpieces of various shapes and cross-sectional configurations which does not require a change-over of induction coils for each difierent workpiece size or type.

Still another object of the invention is to provide an induction heating furnace which does not require a change-over of induction coils for workpieces of various shapes and cross-sectional configurations, but which nevertheless employs the same number of parts which are required for a conventional induction heating machine of the type described above.

In accordance with the invention, a plurality of parallel induction coil assemblies of differing cross-sectional sizes and shapes are mounted side-by-side on a base member with their forward ends aligned. Extending transversely of the coil assemblies, adjacent their forward ends, is a track structure or guideway which carries a carriage having a hydraulic cylinder billet-pushing mechanism mounted thereon. The hydraulic cylinder is mounted on the carriage whereby it may be aligned with any of the parallel coil assemblies by merely traversing the carriage on the guideway to a position directly in front of the particular coil assembly required. Thus, if it is desired to heat rectangular billets, for example, the carriage will be positioned on the guideway so that the billet pushing mechanism is aligned with the coil having the matching rectangular configuration, whereupon successive billets will be pushed into the coil as in any heating operation. If it is then desired to heat round billets, the carriage and pushing mechanism will be positioned on the guideway in front of the coil having a circular cross section of the proper diameter. Thereafter, if it is necessary to heat hexagonal billets, the carriage will be positioned 3,fi57,986 Patented Oct. 9, 1962 in front of a hexagonal coil, and so on. Notwithstanding the fact that billets of different sizes and shapes can be heated with this equipment, only the one billet pushing mechanism is required; and since the coils are all mounted on the base member, it becomes unnecessary to make time-consuming change-overs for each different type of billet and provide storage space for the coils not being used.

In accordance with another aspect of the invention, only a single power factor-correcting capacitor assembly is required for the entire plurality of induction coils. As will be seen, the capacitors are mounted in the base structure and may be connected to the particular coil being used by means of detachable bus bars, it being understood that the capacitors will be connected to only a single coil at any one time. Thus, the equipment requires the same number of parts as a conventional induction heating arrangement while having the many advantages outlined above.

The foregoing and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which from a part of this specification and in which:

FIGURE 1 is a top View Of an induction heating machine constructed in accordance with the teachings of the present invention;

FIGURE 2 is a side View of the apparatus shown in FIGURE 1; and

FIGURE 3 is a cross-sectional view taken along line III-III of FIGURE 2.

Referring to FIGURES 1 and 2, the apparatus shown includes a base structure 10 on which are mounted a pair of parallel induction coil assemblies 12 and 14. In the particular embodiment of the invention shown herein, each of the coil assemblies is formed from four aligned coil structures A, B, C and D, with the coil structures A and B being connected in series through bus bars '16 and 18 and the coil sections C and D being connected in series through bus bars 20 and 22. In accordance with the usual practice, each of the coil sections A, B, C and D comprises a hollow copper tube 24 wound in a helical configuration and embedded in a generally rectangular casing 26 formed from cast refractory or other similar insulating material. Suitable connections, not shown, are provided for conducting a cooling liquid through the interior of the hollow copper tube 24 to carry away the heat generated during the induction heating operation.

As is best shown in FIGURE 3, the coil assembly 14 has a rectangular passageway 28 extending therethrough while the coil assembly 12 has a circular passageway 33. Thus, rectangular billets may be heated in the one coil assembly while circular billets may be heated in the other. Extending along the inner periphery of each of the passageways 28 and 3b are a plurality of guide rails 32 which are held in position by means of tie rods 01' clamping mechanisms 34 which extend through the con crete casing 26 of each coil section at the opposite ends thereof. As was the case with the induction coil, suitable connections, not shown, are provided for conducting a cooling liquid through the guide rails 32..

Referring to FIGURE 3, the base structure it) comprises a frame constructed from angle irons 36 or the like having removable panels secured to either side. Disposed within the base structure are a plurality of capacitor assemblies 38 having bus bars 40 and 42 connected thereto which extend upwardly through the top of the base structure and between the coil assemblies 12 and 14. As shown in FIGURE 1, a pair of bus bars 40 and 42 is provided for each pair of serially-connected coil sections A and B, or C and D. Bolted to the top of bus bars 40 and 42 are removable 'U-shaped bus bar sections 44 and 46 respectively, each of which is adapted to be connected to one of the two input terminals 48 or 50 for each pair of serially-connected coil sections A and B, or C and D. It will be noted that the bus bars 40 and 42 are disposed midway between the coil sections 12 and 14. Consequently, the members 44 and 46 may be connected to the coil sections in either one of the coil assemblies 12 or 14. That is, if it is desired to heat round billets in coil section 12, the sections 44 and 46 will be bolted to the input terminals 48 and Sit on coil sections A and B, and C and D, in coil assembly 12. If it is then desired to heat rectangular billets, the U-shaped sections 44 and 46 will be disconnected from coil assembly 12 and connected to the input terminals 43 and 50 of the respective serially-connected coil sections in assembly 14. As will be understood, means, not shown, are provided to connect the bus bars 41) and 42 to a source of alternating current voltage. In this manner, only one set of capacitor assemblies 38 and one pair of bus bars 40 and 42 need be provided for each pair of serially-connected coil sections A and B or C and D in the two assemblies 12 and 14. It will be noted that any one coil may be used to replace in service any one of two coils merely by reversing it. For example, coil A may be turned around to replace coil B or coil D. Similarly, coil B may be turned around to replace coil A or coil C and so on. This feature, of course, requires a fewer number of replacement parts.

Referring now to FIGURES 1 and 2, the left end of the base structure has a pair of I-beams 52 and 54 positioned on its upper surface and extending transverse to the longitudinal axes of the coil assemblies 12 and 14. Welded or otherwise securely fastened to the tops of the I-beams 52 and 54 are a pair of guideways or tracks 56 and 58 having slots 60 and 62 extending along their lengths. Slidable on the guideways 56 and 58 is a carriage 64 comprising a plate 66 having elongated bars 68 and 70 on its lower surface which extend into the slots 60 and 62 provided in the guideways. At the forward end of plate 66 is a V-tray 72 which is arranged to hold a billet in axial alignment with one of the coil assemblies 12 or 14 prior to its being pushed into the interior of the coil. Adjacent the V-tray 72 is an inclined chute 74 adapted to receive a plurality of billets which are to be heated. Positioned above the V-tray 72 on plates 76 and 78 is a hydraulic cylinder 80* which actuates an escapement mechanism 82 for permitting successive single billets on the inclined chute 74 to roll into the V-tray 72 preparatory to a heating operation. The escapement mechanism 82, not shown in detail, comprises a block having an opening therein which may be moved by clinder 80 to a position where a billet may roll into the opening and against the side of the V-tray 72. After a billet has thus been positioned in abutment with the side of the V-tray, the hydraulic cylinder 80 will be actuated to elevate the escapement mechanism S2 whereby the billet positioned in the opening will be raised to a position where it will roll or slide into the V-tray. During this time, the lower portion of mechanism 82 acts as a stop to prevent downward movement of billets on the chute 74 until the opening is lowered to permit the stack of billets to load the escapernent mechanism preparatory to its next elevating or loading operation.

To feed billets into the interior of coil assembly 12 or 14, there is provided a pusher rod 86. Reciprocatory motion is imparted to the rod 86 by means of a hydraulic cylinder, generally indicated at 88, which is bolted or otherwise securely fastened to the plate 66, the arrang ment being such that the cylinder 88, the V-tray 72 and the inclined chute 74 may be moved on the guideways 56 and 58 as an integral unit. In the position shown in FIGURE 1, the cylinder 88 and the V-tray 72 are aligned with the coil assembly 14; Under these circumstances, rectangular billets will be fed onto the V-tray 72 in succession from inclined chute 74. As will be understood, after each billet is positioned on the \i-tray 72, it is pushed into the interior of the coil assembly 14 by cylinder 88. On the other hand, if it is desired to heat round billets, the plate 66 and the components carried thereby will be shifted downwardly as shown in FIGURE 1 to a position where the cylinder and V-tray are aligned with coil assembly 12. Under these conditions, round billets will be disposed on inclined chute 74 and fed in succession into the interior of coil assembly 12. It will be noted that the feed mechanism of elements 72, '74, 86, 88 etc. will accommodate billets of any cross-sectional configuration or size. That is, no change-over of parts in the feed mechanism is required for different types and sizes of billets.

In a typical heating operation, the cylinder 83 and V-tray 72 will be positioned in front of the proper coil assembly, and successive billets on inclined chute 74 will be fed into that coil assembly, the arrangement being such that each billet will be pushed through the coil sections A, B, C and D by the action of cylinder 33 in pushing subsequent billets into the entrance end of section A. Thus, each billet will travel through the successive coil sections until it falls onto a common exit chute 90. Driven V-shaped rolls 92 and 94 may be provided to assist in the ejection of billets from the respective coil assembly 12 or 14.

It can thus be seen that the present invention provides an induction heating machine adapted to heat billets of various cross-sectional shapes and sizes without requiring a change-over of coils for each billet size or shape heated. At the same time, the induction heater requires no additional parts over and above those which would be required in a conventional heater of the type having a single induction coil assembly mounted thereon. That is, only the single hydraulic cylinder 88 is required as in a conventional heater and, similarly, only one set of power factor-correcting capacitors 38 is required even though a plurality of coils are mounted on the equip ment. If one of the coil assemblies 12 or 14 should need minor repairs or a complete overhauling, the other coil section may be operated while the repairs are being made, thereby avoiding costly shutdowns.

Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention. In this respect, it will be apparent that although only two induction coil assemblies 12 and 14 are shown herein for purposes of explanation, the number of coil sections may be extended indefinitely by merely Widening the base structure 10, adding more bus bar electrical connections, and lengthening the guideways 56 and 58.

Having thus described our invention, we claim:

1. An induction furnace comprising a plurality of separate open-ended induction coils arranged side-byside, a first member movable along a path extending transverse to said separate induction coils adjacent the open ends thereof, a second member mounted on said first member and movable from a position remote from the open ends of the induction coils to a position directly in front of said open ends whereby the second member may push a workpiece into the open end of a selected one of said separate induction coils determined by the position of the first member along said path and a means for feeding workpieces onto said first member as said second member remains in the same position on said path.

2. An induction furnace comprising a plurality of openended induction coils arranged side-by-side, a track structure extending transverse to the axes of said'induction coils adjacent the open ends thereof, a carriage movable along said track structure, a single device mounted on said carriage to feed workpieces axially forwardly into the interior of a selected one of said induction coils determined by the position of the carriage on said track structure and means for intermittently feeding workpieces onto said single device as the carriage remains in the same position on said track.

3. Apparatus for inductively heating workpieces of various cross-sectional configurations comprising, in combination, a plurality of parallel induction coil assemblies of different cross-sectional configurations arranged sideby-side, a carriage movable along a path extending transverse to the longitudinal axes of said coil assemblies at one end thereof, and single means on said carriage to feed successive single workpieces axially forwardly into a selected one of said coil assemblies, the arrangement being such that the carriage may be moved into any one of a plurality of positions where the means to feed will be in general alignment with an associated one of said coil assemblies.

4. Apparatus for inductively heating workpieces of various cross-sectional configurations comprising, in combination, a plurality of parallel induction coil assemblies of dilferent cross-sectional configurations, said coil assemblies being arranged side-by-side whereby their longitudinal axes lie in a common plane and their forward ends are substantially aligned, a carriage movable along a path extending transverse to the longitudinal axes of said coil assemblies at the forward ends thereof, and a single device on said carriage to feed workpieces axially forwardly into a selected one of said coil assemblies, the arrangement being such that the carriage may be moved into any one of a plurality of positions where said device may be actuated to force a workpiece axially forwardly into the interior of an associated coil assembly.

5. Apparatus for inductively heating workpieces of various cross-sectional configurations comprising, in combination, a base member, a plurality of parallel induction coil assemblies of different cross-sectional configurations mounted on said base member and arranged side-by-side with their longitudinal axes lying in a common flat plane and their forward ends substantially aligned, a track structure on the base member extending substantially perpendicular to said coil assemblies at the forward ends thereof, a carriage movable along said track structure, and a single pushing device on the carriage for feeding successively single workpieces axially forwardly into an associated one of said coil assemblies, the arrangement being such that the carriage may be moved into any one of a plur-ality of positions on the track structure where the means to feed is aligned with an associated one of said coil assemblies.

6. Apparatus for inductively heating workpieces of various cross-sectional configurations comprising, in combination, a base member, a plurality of parallel induction coils of different cross-sectional configurations mounted on said base member in side-by-side relationship with their longitudinal axes lying in a common fiat plane and their forward ends substantially aligned, a track structure on the base member extending substantially perpendicular to said coil assemblies adjacent the forward ends thereof, a carriage movable along said track structure, a single hydraulic cylinder positioned on said carriage and having a central axis extending parallel to the longitudinal axes of said coil assemblies in said common plane, a piston reciprocable within said hydraulic cylinder means and adapted to push a single work-piece axially forwardly into the interior of a coil assembly, and means on the carriage for feeding a succession of workpieces into a position on the carriage where they are disposed between said hydraulic cylinder means and said coil assemblies, the arrangement being such that the carriage may be moved on the track structure to any one of a plurality of positions where a workpiece positioned in front of said hydraulic cylinder means may be pushed into an associated one of said coil assemblies.

7. Apparatus for inductively heating workpieces of various cross-sectional configurations comprising, in combination, a plurality of parallel induction coil assemblies of different cross-sectional configurations arranged sideby-side whereby their longitudinal axes lie in a common plane, a carriage movable in a direction transverse to the longitudinal axes of said coil assemblies at the forward ends thereof, single means on said carriage to feed workpieces axially forwardly into a coil assembly whereby the means to feed may be moved by said carriage into general alignment with any one fo said coil assemblies, a pair of input terminals adapted for connection to a source of alternating current voltage, and means for selectively connecting said input terminals to any single one of said parallel coil assemblies, the arrangement being such that the input terminals may be connected to the coil assembly in said plurality of assemblies having workpieces fed therein by said means to feed.

8. Apparatus for inductively heating workpieces of various cross-sectional configurations comprising, in combination, a plurality of induction coil assemblies of different cross-sectional configurations arranged side-by-side, single means to feed workpieces axially forwardly into the interior of an associated one of said coil assemblies, said means to feed being transportable whereby it may be aligned With any one of said coil assemblies, a pair of input terminals adapted for connection to a source of a1- ternating current voltage, single power factor-correcting means connected across said input terminals, and means for selectively connecting said input terminals to one of said plurality of induction coil assemblies having workpieces fed therein by said means to feed.

9. Apparatus for inductively heating workpieces of various cross-sectional configurations comprising, in combination, a plurality of parallel induction coil assemblies of diiferent cross-sectional configurations arranged sideby-side whereby their longitudinal axes lie in a common plane, a carriage movable in a direction transverse to the longitudinal axes of said coil assemblies at the forward ends thereof, single means on said carriage to feed workpieces axially forwardly into a coil assembly whereby the means to feed may be moved by said carriage into general alignment with any one of said coil assemblies, a pair of input terminals adapted for connection to a source of alternating cur-rent voltage, means for selectively connecting said input terminals to any single one of said parallel coil assemblies, and single power factor-correcting means connected across said input terminals whereby the power factor-correcting means may be used for any one of said induction coil assemblies during the time said input terminals are connected thereto.

10. Apparatus for inductively heating workpieces of different cross-sectional configurations comprising, in combination, a pair of parallel induction coil assemblies of different cross-sectional configurations arranged sideby-side whereby their longitudinal axes lie in a common plane, single means to feed workpieces axially forwardly into the interior of an associated single one of said coil assemblies, said means to feed being movable in a direction transverse to the coil assemblies at one end thereof whereby it may be aligned with either one of said coil assemblies, a pair of electrical bus bars disposed between the coil assemblies, single power factor-correcting means connected across said bus bars, and adjustable means for selectively connecting said bus bars to either one of said coil assemblies while disconnecting the other coil assembly therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 1,764,647 Roscoe June 17, 1930 2,428,705 Finger Oct. 7, 1947 2,939,591 McLaughlin et a1. June 7, 1960 

